One vertex per element, one color per generator, with an edge from x to x·s.
(3,7)(6,8)(9,10,14,20,16,22,15,21)(11,23,27,17,28,40,26,30)(12,29,31,25,33,37,32,18)(13,19,36,39,35,24,34,38)(2,5)(3,7)(9,11)(10,17)(12,24)(13,29)(14,26)(15,27)(16,28)(18,36)(19,33)(20,23)(21,40)(22,30)(25,34)(31,39)(32,38)(35,37) involution — undirected(1,2)(3,6)(4,5)(7,8)(9,12,15,32,16,33,14,31)(10,18,20,29,22,25,21,37)(11,24,27,38,28,19,26,39)(13,30,34,40,35,17,36,23)(2,5)(6,8)(9,13,14,36,16,35,15,34)(10,19,20,39,22,24,21,38)(11,25,27,37,28,18,26,29)(12,30,31,23,33,17,32,40)(1,3,4,7)(2,6,5,8)(9,14,16,15)(10,20,22,21)(11,26,28,27)(12,31,33,32)(13,34,35,36)(17,23,30,40)(18,29,25,37)(19,38,24,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.